Soil warming accelerates decomposition of fine woody debris

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Plant and Soil 356 (2012): 405-417, doi:10.1007/s11104-012-1130-x.Soil warming from global climate change could increase decomposition of fine woody debris (FWD), but debris size and quality may mitigate this effect. The goal of this study was to investigate the effect of soil warming on decomposition of fine woody debris of differing size and quality. We placed FWD of two size classes (2 × 20 cm and 4 × 40 cm) and four species (Acer saccharum, Betula lenta, Quercus rubra and Tsuga canadensis) in a soil warming and ambient area at Harvard Forest in central Massachusetts. We collected the debris from each area over two years and measured mass loss and lignin concentration. Warming increased mass loss for all species and size classes (by as much as 30%), but larger debris and debris with higher initial lignin content decomposed slower than smaller debris and debris with lower initial lignin content. Lignin degradation did not follow the same trends as mass loss. Lignin loss from the most lignin-rich species, T. canadensis, was the highest despite the fact that it lost mass the slowest. Our results suggest that soil warming will increase decomposition of FWD in temperate forests. It is imperative that future models and policy efforts account for this potential shift in the carbon storage pool

Dynamics of woody debris in a beech stand (Fagus sylvatica L.) in Solling. Input, causes and decomposition of woody debris

In a 8 ha beech (Fagus sylvatica) stand of about 160 years in Solling, south Lower Saxony, the input and decomposition of woody debris were observed over a period of 12 years. Since the beginning of the investigation input has increased. In 2000 the volume of the coarse woody debris was 50,9 m 3 ha I (Tab. 4). Storm and the white rot resulting fungus Fomes fomentarius were identified as causes of mortality (Fig. 1). The infestation of Fomes fomentarius increased and resulted in death of single trees (Fig. 3). The oldest, still identifiable, strongly decomposed logs fell down 1970. Under the given climatic conditions the decomposition period is about 40 years. The determined volume of woody debris is in the range of the amounts from natural beech forests and natural forest reserves. The results indicate that the amount and origin of mortality as well as the mortality pattern depend on the age of the stand. On the basis of the properties of woody debris a decomposition key will be presented